An efficient enzyme-responsive controlled release carrier system was successfully fabricated using single-stranded DNA encapsulated functional mesoporous silica nanoparticles. Mesoporous silica nanoparticles were initially fabricated through hydrolysis of tetraethyl orthosilicate (TEOS) in cetyltrimethylammonium chloride (CTAC) solution, and the surface of nanoparticles could be encapsulated with single-stranded DNA. This nanomaterial has excellent bioactivity and its hydrolysate cannot cause damage to normal cell, thus the biocompatibility of the nanomaterial is improved. In addition, this nanomaterial showed an excellent drug release performance when loaded with drugs, which would be helpful to increase the treatment efficiency and decrease side effects of drugs.
Abstract There are potential effects of converting a planted-forest type from conifer to broadleaf or mixed-species on soil organic carbon (SOC) chemical composition, and the quantity and distribution of various chemical compositions of SOC remain uncertain. An afforestation experiment with different tree species (Pinus massoniana, Erythrophleum fordii [N-fixing species], and mixed P. massoniana and E. fordii) was conducted in clear-cut sites of P. massoniana-planted forests in a subtropical region. Topsoil organic C quality and microbial diversity were assessed after eight years of afforestation. Referring to the species diversity index in the community, Pielou’s evenness index was used for estimating the evenness of distribution of various organic C compositions in the total organic C of soil, litter, and fine roots. The proportions of alkyl C and carbonyl C in SOC, as well as the alkyl C/O-alkyl C (A/O-A) ratios and the distributed evenness of the four main SOC chemical compositions were higher in the monospecific E. fordii and mixed-species-planted forests than in the monospecific P. massoniana-planted forest. Positive relationships of the A/O-A ratio and the evenness of distribution of various SOC chemical compositions in the litter as well as fine root C quality were observed. Microbial biomass C was positively correlated with the labile SOC (O-alkyl C). Multivariate analysis showed that the fine roots had a closer correlation with the chemical composition of SOC than the litter. These results highlight that introducing native N-fixing broadleaf tree species and mixing N-fixing species into conifer forests probably enhances the SOC chemical stability. It also minimizes the risk of C decomposition posed by any one soil organic matter (SOM) constituent having a huge impact during climate change through increasing the proportion of recalcitrant C components and even distribution of various SOM chemical compositions.
Under the pressures from growing population, arable land diminishment, yield limitation of major grain crops, global climatic change, etc, there is a latent crisis in Chinese food security. Potato, as the fourth major crop, plays a vital role in alleviating food problem considering its great nutritive value, high yield and adaptability. Chemical fertilizers and pesticides (CFPs) are implicated in ensuring stable and high yields of potato. Therefore, CFPs were intensively used for boosting up the yield; however, the use intensity of CFPs exceeds the international recognized standard, resulting in negative impacts on environment quality, agri-ecosystem, land productivity and tuber production cost. Consequently, those obstacles mentioned above jeopardized the sustainability of potato industry. In order to solve the dilemma, this article focuses on the analysis of the major reasons for abuse of CFPs, and further identified that the excessive consumption could be attributed to high application intensity, low utilization efficiency and lack of scientific application methods. Furthermore, this article introduces the technological advances and future trends in chemical fertilizer and pesticide reductions (CFPR) of developed countries. Based on the successful CFPR experiences abroad, the article also provides some development strategies for Chinese potato CFPR. (1) Promote legislation curbing application rate of potato CFPs. Several research projects were initiated to investigate the scientific standard of application amount for CFPs. Once the scientific standards were set, they could be gradually legislated into agricultural laws to stipulate the use of CFPs nationwide. (2) Promote the innovation on high-efficient application technology and encourage the use of green alternatives to chemical controls. Efforts on scientific research and education should be strengthen to speed up the innovation/application of advanced CFPR techniques. In addition, recognized reduction techniques abroad could be transferred to improve our application practices in pursuit of chemical contamination decreases. Some chemical fertilizers could be replaced by organic fertilizer, or they could be used in combination with organic fertilizers to enhance use efficiency. Chemical pesticides, to some extent, could be substituted by efficient, low toxicity/residue pesticides, and green prevention techniques could be employed to avoid pesticide abuse. (3) Promote the invention/improvement of intelligent agro-equipment with precision application capabilities. Unlike developed countries, the majority of Chinese potato production entities is still dispersible, small-scale, traditional family farms. Hence, modern fertilizer/pesticide machinery including deep fertilization and accurate spaying should be developed accordingly to meet specific needs of Chinese farmers. However, in the large-scale and intensive potato-growing area of north China, it is reasonable for the large potato enterprise and cooperatives to introduce advanced equipment and management system overseas. (4) Integration of multiple CR technologies to meet diverse regional needs. Combined with traditional reduction techniques such as soil testing, formulated fertilization, drip-fertigation and integrated pest-control, newly developed reduction technology could be integrated into regional “Potato Chemical Fertilizer and Pesticide Reduction” technique systems according to the diverse ecological, climatic and cultivating factors. Through demonstration zones and potato-grower trainings, popularization of reduction techniques would benefit the potato-growing farmers and cooperatives, which would significantly reduce the use of CFPs in China.
Merkel cells, discovered by Friedrich Sigmund Merkel in 1875, are found in multiple regions of the skin and some mucosa and make contact with specialized nerve fibers, participating in the perception of touch. However, Merkel cells have thus far not been described on the ocular surface. The purpose of this study was to investigate the distribution and ultrastructure of Merkel cells on the ocular surface and study changes in their number and ultrastructure after corneal epithelial wounding. Entire mouse ocular surfaces were obtained and stained by antibodies and tracking dye on fixed whole-mount specimens. The distribution and ultrastructure of specific fluorescence-positive cells were analyzed using deconvolution microscopy and transmission electron microscopy (TEM), respectively. The corneal epithelial wound-healing model was employed to observe the ultrastructural changes of these CK8-positive cells. We found that CK8-positive cells and FM1-43-positive cells were mainly located in the stromal layer, but not in the epithelial basal layer, of the forniceal conjunctiva. Our TEM results indicate that these cells possess the unique characteristic structures of Merkel cells, including electron-dense membrane-surrounded granules and spine-like protrusions of variable lengths, and demonstrate the formation of Merkel cell-neurite complexes. After corneal epithelial wounding, these cells exhibited rapid cell shrinkage and nuclear lobulation. Thus, Merkel-like cells were found in the conjunctival stroma of the ocular surface and may play an important role in maintaining the normal physiological function of the ocular surface.
Transgenic mice were used to study the effect of the neural tube on somite myogenesis. These mice express a transgene in which the 1 kb DNA 5' regulatory sequence of the desmin gene is linked to a reporter gene which codes for E. coli beta-galactosidase. In order to determine whether the developmental fate of cells, specifically the prospective myogenic population, in newly developed somites was pre-determined, newly formed somites were isolated from the caudal region of day 9.5 transgenic embryos and transplanted into 8.5 day non-transgenic host embryos. Even though the implanted somites were not oriented in the host embryos, all the specimens examined developed normally at the graft site forming a dermatome, myotome and sclerotome in the correct anatomical positions. The myotome even expressed the desmin transgene. In addition, we isolated the 3 most caudal somites, that is, the most recently developed somites, from day 9.5 transgenic embryos and maintained them on gelatin-coated coverslips in culture for up to 4 days. While these somite explants did not develop myoblasts, it was possible to induce myogenesis by introducing pieces of neural tube into the explant cultures. These results suggest that the developmental fate of cells within the newly formed somite is not predetermined, but is dependent on the microenvironment surrounding the developing somite.
It is known that in adult mammals, the heart has lost its regenerative capacity, making heart failure one of the leading causes of death worldwide. Previous research has demonstrated the regenerative ability of the heart of the adult Xenopus tropicalis, an anuran amphibian with a diploid genome and a close evolutionary relationship with mammals. Additionally, studies have shown that following ventricular apex resection, the heart can regenerate without scarring in X. tropicalis. Consequently, these previous results suggest that X. tropicalis is an appropriate alternative vertebrate model for the study of adult heart regeneration. A surgical model of cardiac regeneration in the adult X. tropicalis is presented herein. Briefly, the frogs were anesthetized and fixed; then, a small incision was made with iridectomy scissors, penetrating the skin and pericardium. Gentle pressure was applied to the ventricle, and the apex of the ventricle was then cut out with scissors. Cardiac injury and regeneration were confirmed by histology at 7-30 days post resection (dpr). This protocol established an apical resection model in adult X. tropicalis, which can be employed to elucidate the mechanisms of adult heart regeneration.
Every year, a large amount of tobacco waste liquid (TWL) is discharged into the environment, resulting in serious pollution for the environment. In this work, a TWL-based particle (OACT) was fabricated by CaO, attapulgite (ATP), and TWL, and, then, OACT was coated by amino silicon oil (ASO) to form OACT@ASO. Therein, OACT@ASO had high controlled-release ability for fulvic acid (FA), because of the nanonetworks structure for ATP and the high content of FA in TWL. The release ratio (RR) of FA from OACT@ASO reached 94% at 75 h in deionized water, and 23% at 32 d in silica sand. Furthermore, the release mechanism of FA from OACT@ASO was consistent with the First-order law. Additionally, OACT@ASO also possessed high immobilization capacity for Cu(II), Cd(II), and Pb(II) (CCP) in soil. Notably, a pot experiment indicated that OACT@ASO could facilitate the growth of pakchoi seedlings and decrease the absorption of CCP by pakchoi seedlings. Thus, this study provides a new kind of organic fertilizer which could not only release FA, but also immobilize CCP in soil.
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